Signal system



Mar. 3. 1925. 1,528,596

c. E. BEACH SIGNAL SYSTEM Filed Nov. 5, 1919 3 Sheet5-Sheet 1 Fig.1.

Mar. 3. 1925. 1,528,596

. C. E. BEACH SIGNAL SYSTEM Filed Nov. '5, 1919 s sheeti-"sh t 2 4 o 9 o A O o O O o 0 F2344 F23 5.

\ INVENTOR Mar. 3. 1925. 1,528,596

C. E. BEACH SIGNAL SYSTEM Fild Nov. 5, 1919 3 3 SheetI-Sheet 5 Patented Mar. 3, 1925. Q

o, UNITEDMSITATJEVS PAT CLARENCE E. BEACH, OF IBINGHAMT ON, NEW YORK.

SIGNAL sysrmu.

-. Application filed November 3, 1919. Serial No. 335,430.

To (2 whom it may concern:

Be it known that I, CLARENCE BEACH, a citizen of the United States, residing at Binghamton. county of Broome, and State of New York, have invented certain new and useful Improvements in Signal Systems, of which the following is a specification.

This invention relates to electrical signal systems employing a plurality of conductors, and is particularly adapted for use in systems employing such conductors in varying c0mbinations,such as, for example, emergency si al systems provided for fire alarm, night watch and similar service. and comprising a central station having suitable current supply and manifesting mechanism, a plurality tions having circuit-breaking and circuitgrounding mechanism, and a normally closed line-circuit in which such stations are connected. Systems have heretofore been devised ,in which manually or automatically operable switches were provided whereby, in case of grounding, breaking. or crossing of the line wires of such a circuit, the stations on both sides of the break or ground may be quickly placed in operative connection with the central stat-ion instruments,and other systems have heretofore-been devised in which duplicate signal manifesting mechanisms were provided at the central station, connected in the respective sides of such a circuit, sothat. in the event of concurrent activity of any two initiating stations, the signals of such stations could be independently and correctly manifested by such respective central station mechanism; but none of such prior systems have been dependably responsive, without readjustment, under either normal or any of said abnormal conditions.

'It is a well recognized fact that the current paths of signal systems intended to give notification or warning of-emergencies are likelyto be subjected to progressive impairment incident to the development of such emergencies, and that the likelihood ofconcurrentactivity of a plurality of the initiating stations of such a system increases with the gravity and proportions of an emergency. In view of these facts,it is highly importantthat no 7 signal shall be lost through successive or simultaneous develop 7 ment of such circuit conditions, even though the activity of an initiating station is interof distant signal initiating staof a n unintended rupted and all connection between such station. and the central station is destroyed prior to any repetition of its signal.

If such losses are to be avoided, opera.- bility under normal conditions must be attained without recourse to either automatically or manually operable switches which require adjustment subsequent to the development of abnormal conditions, as, by the very nature of-such switches, correct response to intended signal impulses is impaired pending, and incident to, such switches following the development of abnormal conditions. Furthermore, responsiveness of such automatic switches depends upon delicate instrument adjustments, the effectiveness of which cannot be readily verified'; and manual switches are not used with suiiicient frequency to enable attendants to become desirably proficient in their timely ad'ustm'ent.

Signal systems, such as those hereinbefore referred .to, frequently comprise circuits of comparatively low insulation and high con:

ductor resistance; thus limiting the electro motive force of the current source, and hence systems, it is therefore needful that suchmechanism shall be responsive to comparatively small changes in the strength of the current flow in the signal circuit, and that the current changes iIr-ident to signals from initiating stations under either normal or abnormal conditions shall be such as to as sure the intended response.

' It is well recognized that the developmentground connection, or an excessive leakage between line conductors and the ground, is detrimental to the depend-' able'operability of any tem, and it is therefore desirable to promptly detect and give suitable warning of such conditions. Various constant test arrange ments have heretofore been devised for the ENT .oFFICE;-

readjustment of electrical signal syspurpose of. assuring such detetion and warning, but the employment of such prior arrangements has incurred opportunities for losses of signals which have been deemed more objectionable than those likely to arise in the absence of such arrangements from the ground connections or. leakage they might detect. Such incurred opportunities have been found to be particularly objectionable' in instances of systems which are, at times, unattended by anyone qualified to makesnitable readjustment of the operating conditions, in the event of the development of an unintended ground connection or leakage such as might so co-operate with the ground connection employed by the testing arrangement as to impair theoperability of the signal circuit to which it was applied.

The main object of this invention is to provide a signal system comprising three or more conductors, and having constantly effective means whereby the interconnection of any two of such conductors will establish a signal current path operatively indcrality of initiating stations so that facilities will be provided, without readjustment,

for the complete and correct manifestation at the central station of signals. from all actuated initiating stations either when the conductors and apparatus of such system are in normal condition or whensuch conductors and apparatus are subjected to any of the following abnormal conditions: series circuit broken at any one or between any two initiating stations; circuit grounded at any one or between any two initiating stations; line wires crossed so as to shunt out any one, more or all initiating" stations broken ground connection at any initiating station or stations; concurrent activity of any two initiating stations; concurrent activity of any two initiating stations while the circuit is broken orgronnded between such stations; line wires crossed at opposite sides of one, more or all initiating stations andbroken at any one point: or line wire broken and direct current 'difierenee of earth potential between the central station ground connection and the ground connection of an active initiating station sub-. stantially equivalent to that of the signal circuit current source.

'Other objects of this invention will be in part obvious and in part specifically set forthin the following specification.

'In constructing this invention, electromotive forces differing in phase from one another are provided for the energization of respective signal circuit current paths. Thus, in the instance of a normally closed metallic circuit from which signals should be. received in response to either circuitbreaking or circuit-grounding, three such electromotive forces should be provided.

In any event, there should be at least as the meaning ordinarily intended when this word is employed in referring to electrical circuits and appliance of various polyphase systems which develop'two or more electromotive forces differing in phase from one another by a constant angle, but, as herein employed, the word phase is intended 1. include any recurrent difference between two or more developed electromotive forces, ,regardless of -whether or not such electromotive forces are equal in effective value. regardless of whether they are subject to corresponding variations, and regardless of whether they differ in phase in correspond ing degrees. I

-For example,what is ordinarily termed a single phase alternating current source is capable of such utilization iniaccordance with this invention thatit will provide two electromotive forces differing in phase from one another,in the broad sense in which the subject of phase relation is herein treated.

For further example,it should be noted-that, under certain circumstances, one or more direct current sources can be so employed that, through the co-operation of pole-changers, distributors, interrupters or other similar instrumentalities, or by suitable interconnection between direct current and alternating current sources, pulsations -may be periodically applied to several conductors in orderly sequence.- or may be applied to some of such conductors so that the current fiow in other of such conductors may or may notbe thereby influenced. depending upon the existing connections therebetween.

For the purpose of facilitating the nu.- derstanding of this invention, and for the further purpose of setting, forth in greater detail certain features thereof, a number of embodiments are illustrated in the accompanying' drawings and hereinafter more fully described.

' -in Fig. 1. 4

Like reference characters denote similar parts throughout the accompanying draw,-

I 23, 26 and 27, respectively, said relays bemgs in which,'

Figure 1 is'a diagrammatic representation of a signal system provided with a threephase open-delta cirrrent supply utilized in accordance with this invention.

Figs. 2 and 3 illustrate applications of three-phase closed-delta and star or. Y-connected current Fig. 4 illustrates the application of a so called single-phase alternating current source to such a signal systemas that shown in Fig. 1;

Fig. 5 illustrates a means of co-operatively employing direct and alternating current sources, in accordance with this invention,

for the operation of a signal system such as that shown in Fig. 1. Q

- Fig. 6 illustrates a means, dilfering somewhat from that shown in Fig. 4, for supg plying energy from a (single-phase alternating currentsource for the operation, in accordance with this invention, of a system such as that shown in Fig. 1.

Fig. 7 illustrates an arrangement for utilizing through the co-operation of a polechanger, a direct current source such as a battery, for the operation in accordance with this invention of such a signal system as that shown in Fig. 1.

Figs. 8 and 9 are en arged representations of details of the mec. anism at the initiating stations of Fig. 1, showing the parts in norma and abnormal conditions, respectively.

Referring to Fig. 1,-A diagrammatically indicates a three-phase alternating current generator of suitable frequency, to the terminals of which the primary coils 21 and 22 of suitable t-ranformers are connected through proper line conductors in so-caled with the terminal 26.

open-delta. The coils 23and 2A are the secondary windings of the transformers excited by the primary coils 21 and 22, respectively. One lead from the secondary coil 23 connects with the terminal 25, one .lead from the secondary coil 24 connects with the terminal 27, and a lead from the remaining ends of the coils 23 an'd-24 connects From the foregoing it will 'be apparent that electromotivc forces will be developed for three current paths i. e. between termina-ls 25 and 26, 'between terminals 25 and 27, and between terminals 26 and 27; that such electromotive forces will be developed in such respective current paths in an orderly sequence, will be substantially equal in effective value, and will therefore provide means for the energization of suitable electromagnets upon'the connection of any such magnet between any two of said terminals.

In the utilization of these electrom'otive supply for the system shown be suitably responthe frequency pro- A The remaining ing so constructed as to sive to current flow of duced by the generator terminals'of relays B and D are connected with the centra oilice line-wire terminals 28 and 29, respectively, and the remaining terminal of relay C is connected to the ground.

A three-pen register is diagrammatically indicated at E, comprising the paper tape roll 30. the free end 31 of which passes under the marking ends of the pens 32, 33

and 34. Said pensrare independently operable for the purpose of suitably marking upon the tape 31 in response to energization of the actuating magnets 35, 36 and 37, s respectively.

A suitable register battery 38 is shown, one terminal ofsaid battery is connected to "the armatures of the relays B, C and 'D, and

the other terminal of said battery is connected to one of the leads of each of the magnets 35, 36 and 37. The remaining leads ofmagnets 35 and 37 are connected to the back contacts of relays B' and D, respectively, and the remaining lead of magnet 36 connected to the front cont-act of reav I It isassumed that there will be suitable propelling means for the paper tape 31, but, as pen registers embodying such means are well understood by those skilled inthis art, and as the detailed construction of the registeringmechanism forms no part of this invention. further illustration or description of same is, omitted in the interests of clearness and brevity.

Suitableinitiating stations,.such as F, G, H, I and J, are shown serially connected between the central oflice terminals 28 and 29: the station H being shown on an enlarged scale. so as to facilitate illustration of the code-wheel 39, normally closed contacts 40 and 41. and the normaly open ground contact 42 thereat. a

The code-wheel 39 is so formed that, when at rest. the contact 40 is held in conductive relation with the contact 41. but said contacts are not'raised high enough to bring the contact 41 in conductive relation with the contact 42. During the rotation of the code-wheel 39, each'tooth first raises the contacts 40 and 41 so as to bring them into conductive relation with the contact 42, and then allows all of said contacts to separate one from another. thus providing circuitbreaking and circuit-grounding mechanism.

Suitable means, such as a manual operating handle 43, is provided for causing the actuation of the-code-wheel 39.

'It should be understood that mechanism comprising corresponding instrumentalities is provided at the initiating stations F, G, I and J. a

The operation of the embodiment of this invention illustrated by Fig. l is as follows:

Under normal conditions, the ground contacts 42 of the initiating stations F, G, H, I and J are electrically isolated from the contacts and 41 associated therewith; hence the ground connections of the signal initiating stations are not effective, the relay C will be de-energized, its armature will occupy its retracted position as shown, and register magnet 36 will be de-energized. The line breaking contacts 4Q and 41 of each of the initiating stations will stand closed, and there will be an alternating current flow, through the normal or line circuit current path, which flow will suitably energize relays B and D and thereby hold the armatures of these relays against their front stops, as shown, thereby causing the de-energization of magnets 35 and 37.

The normal current path just referred to, extends from one lead of secondary coil 23 through conductor 51 to terminal 25; thence through conductor 52, relay B, and conductor 53, to the central office terminal 28; thence through conductor 54 to left-hand terminal station. F; thence through con; ductor 55 of said station (as illustrated at station H) to contact 40 thereat; thence through contact 41 and'conductor 56 to the right-hand terminal of, station F; thence through conductor 57 to the left-hand terminal of station G, and correspondingly through station G to. the right-hand terminal thereof; thence through conductor 58 to the left-hand terminal of station H and correspondingly through said station to the right-hand terminal thereof; thence through conductor 59 to the left-hand terminal of station I and correspondingly through said station to the right-hand terminal thereof; thence through conductor 60 to the left-hand terminal of station J and correspondingly through station J to the r1ght-hand terminal thereof; thence through conductor 61 ,to the central ofiice terminal 29; thence through conductor 62, winding of relay D and ,conductor 63 to terminal 27; thence through conductor 64 to secondary-coils 24 and 23 acting in series. While the coils 23 and 24 are thus actin single-phase alternating current will flow between terminals 25 and 27, which current flow will be of substantially'the same effective strength as if either coil 23'or coil 24 was acting alone. i

If now the code-wheel 39 of any intiat- .ing stations should be set in motion, as by the actuation of the operating handle 43 associated therewith, said wheel will first in series, it is evident that a so-called' bring the contacts 40 and .41 into conductive relation with the ground contact 42 associated therewithfand will then permit said contacts to move away from one another; after which the contact 40 will be again moved into conductive relation with contacts 41 and 42 by the next tooth of the code-wheel 39, and this cycle of operation will be repeated such number of times and at such intervals as to formulate the desired code'signal.

Upon the establishment of a conductive relation between contact 42 and the contact 4O and 41 of any initiating station,

as just describedfia current flow will be established through relay C, so as to cause the effective energization thereof, and

thereby'cause the energization of register magnet 36to-actuate register pen 33, which current flow will traverse the following di-' vided path; from terminal 26, through con-' ductor. 66, winding relay C and conductor 67 to ground at 68, thence through the earth to the ground associated with the station the code-wheel 39 of which is being operated. Assuming, for convenience, that the code-wheel of station H is being operated, the current from ground 68 will leave the earth at. ground 71, and pass through conductor 79 to the ,middle terminal of stationH, thence through conductor 78 of of said station tocontact 42 thereof, From contact 42, of the actuated station, two ourrent paths will be provided as follows: one. C

path through contact 41, and conductor 56 to the right-hand terminal of said station; thence through conductor 59, station I, conductor 60, station J, conductor 61, terminal 29, conductor 62, relayD, conductor 63, terminal, 27, conductor 64, secondary. coil 24 and conductor 65 to terminal 26; and the other path through contact 40 and conduc tor 55 to the left-hand terminal of station H; thence tl'iroughconductor 58, station G,

conductor 57, station E, conductor 54, terminal 28, conductor 53, relay B, conductor 52, terminal 25, conductor 51, secondary coil 23 and said conductor 65 to terminal 26.

It is evident that while this divided current pathis effective, as just described, the effectiveness of the energization of res lays B, C and D will be substantially equal; hence throughout the periods when the ground connection of any initiating Sti1-" tion is effective, the armature of the relay C will move to attracted position, and the armatures of relays B and D will-remain in their normal attracted positions.

Whenever the contact 40 of any initiatin station drops into a notch of the code-whee 39 co-operating therewith, said contact 40 -will move away from the contact 41, and

the contact 41 will, at the same time, move away from the contact 42, thus breaking the ground connection and interrupting all cursaid rent flow through the relays B, C and D, and thereby permitting the armatures of relays to move toretracted position. The retractive movement of the armatures of relays B and D will cause energization of the register magnets 35 and 37 and the corresponding nlovement of the armature of why will cause the de-energization of the register magnet 36.

Continued rotation of the acting codewheel 39 will thereafter move the contact 40 associated therewith into conductive relation with its cooperating contact 41, and thereafter move said contacts 40 and 41 into :onductive relation with their associated con- I tact ,42. Such conductive relationship becondition, station W111 cause its tween contacts 40 and 41 will serve tore-establish current flow through the normal current path already described, thereby reenergizing relays B and D, which relays will there-upon act to cause deenergization of register magnets and '37; and such conductive relationship between contacts 40 and 41 and contact 42 will serve to re-establish current flow through the ground path as hereinbefore described, so asto cause reenergization of relay C, which relay will then act to cause ieenergization of register magnet 36.

From the foregoing it will be apparent that, when all current paths are in proper the actuation of any initiating code signal to be reby pens 32, 33 and 34,

corded concurrently produced by the pen 33 although the record will be somewhat advanced, in point of time,

from records produced by pens 32 and 34.

Should the signal circuit broken, for example, at 80, relays B andD will be de-energized,. and re 'ster magnets 35" and 37 will be energize thus giving the intended warning of such a break.

If any initiating station is actuated while the normal current path is interrupted, as by a break at 80, the relay C and either the relay B or the relay D,'as the case may be, will be energized during each of the periods when the contacts 40 and 41 of such station are brought into conductive relation with the co-operating contact 42, and thecode signal of such station will therefore be manifested by the pen 33 and by either the pen 32 or the pen 34.

During any signal, such as just described,

it any initiating station located at the other side of such a break is actuated, the pen 3.2 will manifest the signal of one of said stations and the pen 34 will manifest the signal of the other of such stations, While the pen 33 will produce-arecord comprising the code signals of both of such stations.

Should the code-wheel of any station be brought to rest in a position which presents a notch to its contact 40, thereby interrupting the normaltcurrent path through "pair thereof, the signal of actuation of pen 33 to manifest such defect.

.D (depending upon the position of the actug is actuated, upon such station, it is evident that the defective condition of such station will be correspondingly manifested, and that, pending the reany station connected at either side of such defective station, or of any two concurrently acting sta-' tions connected at opposite sides of such defective station, willbe correctly manifested in the manneralreadynpointed out. Should an accidental leakage to the ground develop, as suggested by the dotted line-81. such. leakage will result in current flow through the winding of the relay C, and the energization of said relay will cause the If any initiating station should be actuated during the continuance of such a ground leak, the signal of such station will cause responsive action of the relay B or the relay ated station in the circuit with relation to such leak) and thereby cause either the pen 32 or the pen 34, as the case might be, to manifest the code signal of such initiating station.

While a station connected at one side of such a leak is acting, if a station connected in the circuit at the opposite side of such a leak is actuated, the code signals of both of such stations will be correctly manifested, one of said signals being manifested by the pen'32 and the other of said signals being manifested by the pen 34/ Should the code-wheel of any initiating station come to rest in a position which ren- 100 of any station come to rest either in a posi- 1 tlon which renders the ground connection effective or in a position which breaks the normal signal current path, the actuation of code signal to be correctly register E. A E

Should the line wires become-crossed, so

as to shunt out any one onmore initiating stations, as suggested-by the dotted line 82; or should the normal current circuited assuggested by the dotted line 83 between the central oflice terminals 28 and 29, no immediate warning would be given by the central ofiice equipment (unless ,such shunt included a ground connection). a

While any station or stations, or the entire normal current path is short-circuited, as just described, if any initiating station grounded station be such station will nevertheless cause its manifested by the path be shorteachoccasion when the 1 rest the signal of 'such station. Under these respond.

circumstances the pens 32 and 34 will not bhould the ground connection be broken at any initiating station, as, for example,

' 10 by the disconnection of the ground wire from the central terminal thereof, the actuation of-said station will cause the de-energization of relays B and D, and hence will cause pens 32,,and 34 to manifest the signal of such station.

in the ground connection of any initiating Although no immediate warning is given of the short-circuiting of all or any part 'of the normal current path, and although no immediate warning is given of a break station,it isevident that notification of such defects will be provided in the following manner. If a signal initiating station 7 is actuated while the normaLline. current path therethrough is short-circuited, the sigpath through such station is short-circuited.

nal of such station will be manifested exclusively' by the pen 33, and the failure of the pens 32 and 34 toLconcurrently act will serve to indicate that the normal current ;When a signal is received from any station the ground connection of which is interrupted, such signal willbe manifested by pens 32 and 34, but the pen 33 will not-act 35 in response thereto; and the failure of said pen 33 to act concurrently with the pens 32 and 34 will serve to indicate that the ground connection of .such station is defective.

If any two signal stations are simultaneously actuated at a time when all current paths are in normal working order, the signal of one of such stations will be manifested by the pen 32 and the signal of the other of such stations will be manifested by the pen 34; and the pen 33 will respond to all impulses of both stations; so 'that'the signals of such stations will be manifested by the pens 32,and 34, respectively without interference.

From the foregoing it will be evident that when the pens 32, 33 and 34 are acting concurrently, the relay 3 and the pen 32 w1ll act responsively to some one initiating station, and the relay D and pen 34 will act in response to the same or some other one initiating station but, dur' the concurrent actuation of two or more initiating stations, neither of said relays or pens will act in response to the impulses of more than one of such stations. On the other hand,inasmuch as the relayC and pen 33will act in response to the impulses to which both relay B and relay D are subjected when two or more signal stations are acting concurrently,it is desirable that when all of the pens are acting concurrently, the code signals shall be read from the records produced bypens 32 and 34'; the record of the pen 33 being considered conclusive as a manifestation of the code signal of an initiatin station only when such record is produced without'concurrent records of the other pens (as would be the case during the actuation of a short-circuited station). I Should several or all of the initiating stations' be concurrently actuated, the actuated station connected in the circuit nearest to the central Ol'l'lCB terminal 28 would be re-' sponded to by relay B, during the operation of such station, to the exclusion of all other stations; and the actuated station connected in the circuit nearest to the central office terminal 29 would be responded to by relay D, during the operation of such station, to the exclusion of all other stations.

F or example, if stations H, I and J are simultaneously actuated, the initial move-- ment of the code-wheel-39 of station H will establish a ground connection thereat, throughout the duration of which connection the armature of the relay B will 'be maintained in attracted position regardless of any circuited interruptions which may result from the actuation of stations I and J; and when, after further rotation of the code-wheel 39 of station H, the first tooth of said code-wheel is withdrawn from the path of its contact 40, the current path through said station will be interrupted, and the relay B will be thus rendered unresponsive to circuit closures or groundings incident to the operation of stations I and J. Succeeding teeth of the code-wheel 39 will first close the current path through station H and immediately thereafter close the groundconnection through contact 42 thereat, so that, throughout the operation. of station H, relay B will be under the control of said station to the exclusion of stations I and J.

For like reasons, relay 1) will be controlled exclusively by station J during the operation thereof.

Inview of the foregoing, it is evident that if more than two stations are actuated at or about the same time, and if such stations act to transmit their respective code signals but once, the complete code signal of one ofsuch stations will be responded to by the relay B, so as tocause a complete and correct manifestation of such code signal by 'the pen 32, and the relay D would respond to the signal of some other station, so as to cause the complete and correct manifestation thereof by the pen 34. Inasmuch as it is common practice in signal systems of the general type contemplated by Fig. 1 to transmit important signals (such as, for example, fire alarms) four or more times, it is evident that'even under the clrcumstances previously actuated stations may be interrupted by subsequently actuated stations in the event that such subsequently actuated stations are connected in the circuit nearerto the central oflice terminals than the previously actuated stations. Y

In the event that the signal circuit con:

ductors are crossed at the opposite sides of one, more, or all of the initiating stations (as, for example, through the paths indicated by the dottdline 82 or 83). and, while the conductors are thus crossed, if the nor- -mal current path is broken at any point thus short-circuited (as at the point 80),'it is evident that the actuation of any initiating station connected in the portion'of thesignal circuit which is thus both brokenand short-circuited will nevertheless be manifested through the response of relay C to the closures to ground incident to the opera- .tion of such station.

1 Should a difference-' in potential exist in the earth between the centraloflice ground .68 and the ground of any initiating station, at a time when the normal current path is interrupted, as at the point 80, it is evident that such earth potential will not prevent the response of the relay C to ground closures of any actuated initiating station, as might be the case if a direct current source of energy was em loyed, as in prior systems.

Referring to ig. 2, the primary coils 221, 222 and 223 are shown connected in delta to the alternating current three-phase generator A the corresponding secondary coils 231, 232 and 233 are. connected delta to the signal circuit terminals 25,26 and 27, and will therefore operate through conductors 52, 63 and 66 as already described in connection with Fig.1.

In Fig. 3 the prlmary coils 321, 322 and 323 are shown instar or "Y-connection with the three-phase generator A while the secminal 26, and the other lead from said coil is connected to the signal circuit terminal 27. The core of such transformer is so proportioned that the primary and secondary phases are interposed, being, for example, y 120 apart. It is,evidentthat the potential of the generator A? will be applied between terminals 25and 26, and that acorrespondingpotential will be applied by the secondary coil 431 between the terminals 26 and 27. It is further evident that the potential applied by the secondary coil 431 will be out of phase with that of the generator A. It is believed that the action of the current source arrangement shown in Fig. 4, inconnection with a signal system such as shown in Fig, 1, will be obvious to those skilled in this art, and same will therefore not be further described herein.

It is evident that the arrangement indicated by Fig. 4 may not be suited to all conditions under which the current source arrangements of F igs.'l, 2 and 3 may be advantageously applied, asthe developed potentials and the effective current values in; the various current paths which may es tablished are likely to differ in much greater degree than in cases of the current source arrangements of F igs. 1,2 and 3.

Referring to Fig. 5,a divided battery a, a is connected between terminals 25 and 27, one end of the secondary coil 531 being connected intermediate the ends of said bat-. tery, and the other end .of said coil being connected to the signal circuit terminal 26, said coil 531 being excited by the primary coil 521 suppliedby the single-phase alternating current sourceA.

In-the operation of this arrangement, in connection with a signal system such as that shown in Fig. 1;it is evident that, under normal conditions, the direct current developed-by the battery (1, a will flow through relayB, initiating stations F, G, H, I and J, and the relay D, between terminals.25 and 27; and that said relays will therefore respond to breaks and closures of said current The effective electromotive force of the ioo coil 53lashould be substantially the sameas that'of the battery. a, a, hence the establishment of a ground connection at any one 1 of the initiating stations will permit a flow of alternating current through the relay C, andthereby cause the energization thereof.

Such alternating current flow will have presentedtheretd'a divided current path including relays B and D, respectively; however, because of the direct current eleotromotive force of the battery a, a, the alternating cur- .rent will tend to divide, flowing alternately It will be apparent that either part of the batery a, a may be employed alone, without destroying the operability of the arrangement shown in Fig. 5.

In the event of the application of the arrangement of Fig. 5 to the system shown in Fig. l with but one of the parts of the battery a, a; it is evident that the normal current flow will be supplied by such battery a, and that, whenever the ground connection of any initiating station became effective, the transformer coil 531 will cause an alternating current flow through the relay C and the ground connections, and that, during flow of such current in one direction, the direct current flow frombattery a will merge therewith, and during current flow in the opposite direction said battery will act in opposition thereto. As a result of such alternate co-operationland opposition of the battery current, the flow through relays B and- D will be of a pulsating character during such alternating current flow, and under manycircumstances it might be found to be more difficult to so proportion the various parts of the system as to assure a desirable degree of equivalency in the effectiveness of the currents which would. flow through the various paths ifthe battery a is not divided than if arranged as shown in Fig. 5.

In Fig. 6, the single-phase alternating currentsonrce A is shown connected to the primary coil 621 of a transformer, one end 9f the secondary coil 622 of such transformer being connected through the non-inductive resistance 90 to the signal circuit terminal 25,- and the other end of said coil being connected through the inductive resistance-91 to the terminal 27 and the terminal 26 being connected to said coil intermediate the ends thereof. Y

In this arrangement it is evident that, under normal conditions, there will be no current flow through. the path including conductor 65, terminal 26 and conductor 66; and that the current flow through-the normal path will traverse resistances 90 and 91, the character of which will tend to develop a difference in phase between the current flowing through the resistance 90 and the conductor 52 and that flowing through the resistance 91 and the conductor 63; which tendency will serve to restrict such current flow to a substantial extent.

If now a ground connection is established at any initiating station of a signal circuit connected to the terminals 25, 26 and 27 of Fig. 6, in the manner indicated by Fig. 1, the current fiow through resistance 90 and 91 will assume a difference in phase corresponding to the difference in the induc tive effect of such resistances, and thereby set up a current flow through relay C to cause the energization thereof.

From the foregoing it will be apparent that the current source arrangement shown in Fig. 6 will operate similarly to that shown in Fig. 1, as already described except for the fact that it may be very. cult to ro- I portion the resistance and'inductance of 90 and 91 so as to assure the degree of uniformity of current flow through the various paths which may be attained under differing conditions in a system the current source of which is arranged in accordance with other figures of the accompanying drawings.

The arrangementof Fig. 7 is suited for use in cases when it is not deemed expedient to employ an alternating current source.

In accordance with this arrangement a primary or secondary battery is supplied, comprising the three groups of cells (1 a and a which groups are connected in series one with another.

Group a and a should preferably con- 8 'tain such number of cells as to afford sub stantially the same effective voltage, which voltage should suitably exceed that of group (E, for reasons to be hereinaftermore fully explained, while grou a should contain such number of cells as to provide a voltage suitable for the-normal current path.

In accordance with this arrangement, relays B and D may be of direct current type, and are arranged in a manner corres onding to that indicated by Fig. 1-. Instea of employing relay C in accordance with Fig. 1, relay 0 is provided with two windings one end of one of said windings being connected to the free terminal of battery group ahand one end .of the other of said windings being connected to the free terminal of battery group a These windings being so connected that, should the remaining ends thereof.be connected together, the flow of current p therethrou'gh will co-operateto energize the magnet of said relay.

Said remaining. ends of the respective coils of the relay 0 are connected through a polechanger P with the ground 68.

The pole-changer P is shown comprising a magnet 92 whose armature 93 is connected through the conductor 94 to the ground 68, the front and back stops of said armature i being connected through the conductors 95 ilnd 96 to respective windings of the reav c.

To'obtain best results, the condensers 97 and 98 -should be connected between the ground conductor 94 and the conductors 95 and 96, respectively, so as to bridge the break gaps between the armature 93 and the front and back stops thereof. i

The battery 99 is connected through the vibrating interrupter 100 withthe winding of the magnet 92, so that the armature 93 will be caused to vibrate between the front and back stops thereof. l 4

The arrangement of the pole-changer mechanism Pis shown for convenience of illustration, but forms no part of this invenother wellknown forms tion, and it is evident that any one of many of automatic polechangers may be substituted for that shown and just described.

The conductors 44' and 45 communicate with the magnet 36 and the battery 38, respectively, as more fully shown in Fig. 1.

It should be understood that batteries 38 and 99 are shown as bein independent of one another, and indepen ent of the main signal circuit current source, merely in the interests of convenience and clearness of illustration.

In actual practice,-the current for the operation of the register -E may, if desired, be secured from the current source provided for the signal circuit; and the energy for the pole-changer P may, if desired, be secured from all or part of the battery groups a, and a Signal circuit terminals 25 and 27, are connected to the respective terminals of battery group a The operation of the arrangement sho in F ig. 7 is as follows: The pole-changer P operates constantly, thus alternately charging and discharging the condensers 97 and 98, andthereby developing a slight pulsating current flow through the windings of the relay 0, which current flow is insuflicient to effectively attract the armature of said relay.

.Battery group a is causing a steady direct current' flow through the normal signal circuit current path between terminals 25 and 27, and thuscausing eflt'ective energization of relays B" and D.

Should the ground connection of any initiating station 'be now established, it is evident that pulsating current flows would be set up through both windings of the relay a, corresponding pulsations in opposite directions would be set up in the con uctors 52 and 63, although the mean effective cur rent flow in both of said conductors would be substantially unchanged. As a result of 'the pulsating energization of the magnet of relay 0, the armature of said magnet-will move to its front stop and thus cause the energization of. magnet 36 to actuate pen 33 i with- Fig. 1.

(see Fig. 1).

From the foregoing it will be apparent that the response of relays B, c and D to all normal and abnormal circuit conditions will be the same for the current source arrangement shown by Fig. 7 as that hereinbeforemore fully described inconnection The purpose of employing battery groups p a and a is to cause, when the ground connection of any initiating station is closed, the development of such pulsating current flows as, will be substantially equal in effectiveness' to the. normal steady current flow through the usual single current path.

ill

In certain cases, sufliciently eiiecti ve results may be obtained without employing the condensers 97 and 98, but, ordinarily,

the use of these condensers "will improve the operating conditions enough to warrant supplying them.

In the light of the foregoing examples, many other current source arrangements will suggest themselves to those skilled in thisart in carrying out the general spirit of this invention, and although certain parts of the arrangements shown herewith form features of this invention, the broad feature of this invention is not limited to any such arrangements.

The aspect of this invention which is shown inFig. 7 is not herein specifically claimed, as same' forms the subject matter of my co-pending application, Serial No. 666,744, filed October 5th, 1923, as a division hereof.

What I claim herein and desire to-secure' by Letters Patent of the United States is:

1. In a signal system,a normally closed signal circuit lo0p,'a common return conductor associated therewith, 'and means for applying a suitable electromotive force be tween the respective ends of said loop and for applying an electromotive force of sub stantially equivalent mean effectiveness alternately between said loop ends and said conductor.

2. In a signal system,'a normally closed signal circuit loop, a common return conductor associated therewith, a manifesting device to one terminal of which said conductor is connected, and means for applying a suitable electromotive force between the respective ends of said loop and for applying an electromotive force of substantially equivalent mean effectiveness. alternately between said loop ends and the other terminal of said device.

3. In a signal system, a normally closed signal circuit loop serially including manifesting means, a common return conductor associated with said loop, and means for applying a suitable electromotive force be- 4. In a signal system,-a normally closed signal circuit loop including manifesting means at the ends thereof, a common return conductor associated with said loop, and means for applying a suitable electromotive force between the respective ends of said loop and for applying an electromotive force of substantially equivalent mean effectiveness alternatively between said loop ends and said conductor.

5. In a signal system,a normally closed signal circuit loop including manifesting means, a common return conductor associated with said loop, a manifesting device to conductor is connected, and means for applying a suitable electromotive force between the respective ends of said loop and for applying an electromotive force of substantially equivalent mean effectiveness alternately between said loop ends and the other terminal of said device.

7. In a signal system,'-a circuit having signal initiating stations and manifesting means suitably connected thereto, a common return conductor associated with said ohcuit, and means for applying a suitable electromotive force between the ends of said circuit and for applying an electromotive I force of substantially equivalent mean effectiveness alternately between said circuit ends and said conductor.

8. In a signal system,-a circuit havingof substantially equivalent mean effectiveness alternately between said circuit ends and said conductor.

9. In a signal system,a circuit having signal initiating stations and manifesting means suitably connected thereto, a common return conductor associated with said circuit, a manifesting device to one terminal of which said conductor is connected, and

means-for applying a suitable eletromotive force between the respective ends of said circuit and for applying an electromotive force of substantially equivalent mean efends and the other terminal of said de-i fectiveness alternately between said circuit ends and the other terminal of said device;

10. In a signal system,-a circuit having signal initiating stations suitably connected thereto, manifesting means connected at the ends of said circuit, a common return con- "ductor associated with said circuit, a manifesting device to one terminal of which said conductor is connected, and means for applying a suitable electromotive force between the respective ends of said circuit and for applying an electromotive force of substantially equivalent mean effectiveness alternately between said circuit ends and the other terminal of said device. 11. In a signal system,a circuit havin manifesting means and signal initiating stations suitably connected thereto, said stations each comprising means for formulating a code signal, a common return conductor associated with said circuit, and means for applying a suitable electromotive force between-the respective ends of said circuit and for applying an electromotive force of substantially equivalent mean effectiveness alternately between said circuit and said conductor. p

12. In a signal system,-a circuit having manifesting devices included at the ends thereof, signal initiating stations suitably connected to said circuit and each comprising means for formulating a code signal, a common return conductor associated with said circuit, and means for applying a suitable electromotive force between the re spective ends of said circuit and for applying an electromotive force of substantially equivalent mean effectiveness alternately between said circuit ends and said conductor.

13. In a signal system,a circuit having manifesting means and signal initiating stations suitably connected thereto, said stations each comprising means for formulat ing a code signal, a common return conductor associated with said circuit, a manifesting device to one terminal of which said conductor is connected, and means for applying a suitable electromotive force between the respective ends of said circuit and for applying an electromotive force of substantially equivalent mean effectiveness alternately between said circuit ends and the other terminal of said device.

14:. In a signal system,a circuit having signal initiating stations suitably connected thereto and each com rising means for formulating a code signa manifesting means included at the ends of said circuit, a common return COIldllftOI' associated with said circuit, a manifesting device to one terminal of which said conductor is connected, and means for applying a suitable electromotive force between the respective ends of said circuit and for applying an electromotive force of substantially equiva- --ends of lent mean eflectiveness alternately between such circuit ends and the other terminal of said device.

15. In a signal system,-a circuit having an associated common return conductor and connecting signal-initiating stations and manifesting means, said stations each comprising means for governing the effectiveness of a connection between said conduc tor'andl said circuit, and means for applying az-s uitable electromotive force between the said circuit and for applying an electromotive force of substantially equivalent mean effectiveness alternately between said circuit ends and, said conductor.

16. In a signal system,.a circuit having an associated common return conductor and including manifesting devices at the ends thereof, signal initiating stations suitably connected to said circuit and each comprising means for governing the effectiveness of a connection between said conductor .and said circuit, and means for applying a suitable electromotive force between the respective ends of said circuit and for applying an electromotive force of substantially V terminal of which lent mean effectiveness equivalent mean effectiveness alternately between said circuit ends and said conductor.

17. In a signal system,a circuit having an associated common return onductor and connecting signal initiating stations and manifesting means, said stations each comprisin means for governin the effective ness ofa connection between aid conductor electromotive force between the respective ends of said circuit and for applying an electromotive force of substantially equivalentmean. effectiveness alternately between said circuit ends and said conductor.

20. In a signal system,a circuit having an associated common return conductor and including manifesting devices at the ends thereof, signal initiating stations suitably connected to said circuit and each comprising means for formulating a code signal and for governing the effectiveness of a connection between said conductor and said circuit, and means for applying a suitable electromotive force between the respective ends of said circuit and for applying an electromotive force of substantially equivalent mean effectiveness alternately betweensaid circuit ends and said conductor. 1

21. In a signal system,-a circuit having an associated common return conductor and connecting signal initiating stations and manifesting means, said stations each comprising means for formulating a code signal and for governing the effectiveness-of a connection between said conductor and said circuit, a manifesting'device to one termi-- nal of which said conductor is connected, and means forapplying a suitable electromotive force between the respective ends of said circuit and for applying an electromotive force of substantially equivalent mean and said circuit, a manifestin device to oneefi'ectiveness alternately between said cirsaid conductor is connected, andmeans for applying a suitable electromotive force between the respective ends of said circuit and for applying an electromotive force of substantially equivaalternately between said circuit ends and the other terminal of said device.

18. In a signal system,-a circuit having an associated common return conductor and including manifesting means at the ends thereof, signal initiating stations suitably connected to said circuit and each comprising means for governing the effectiveness of a connection between said circuit, a manifesting device to one terminal of which said conductor is connected, and means for applying a suitable electromotive force between the respective; ends of said circuit said conductor and cuit ends and the other terminal ofsaid device.

22. In a signalrsystem,-a circuit having an associated common return conductor and including manifesting means at the ends thereof, signal, initiating stations suitably connected to said circuit and each comprising means for governing the effectiveness of a connection between said conductor and said circuit, a manifesting device to one terminal of which said conductor is connected, and

for formulating a code signal and means for applying a suitable electromotive orce between the respective ends of said circuit and for applying an electromotive force of'substantiaHy .tiveness alternately between such circuit ends and the other, terminal of said device.

23. 'In'a signal system,-a normally closed .signal circuit loop andimeans for applying a suitable electromotive force between the respective endsof said. loop and for applying an electromotive force of substantially equivalent mean effectiveness alternately between said loop ends and the ground.

24. In a signal system a normally closed signal circuit loop, a manifesting device one terminal of which'is grounded, and means equivalent mean efi'ec for applying a suitable electromotive force between the respective ends of said loop andfor applying an electromotive force of with a normally closed signal circuit loop, substantially equivalent meaneifectiveness ,manifesting devices through which the realterhately between said" loop ends and spective endslof said loop are connected to the other terminal of said manifesting two of saidterminals, and a common return 5 device. conductor associated with saidloop and con- 7 25. In a signal system,a normally closed nected to the third of said terminals. signal circuit loop including manifesting 30. In a signal 'system;current supply means at the ends thereof, a manifesting demechanism having three terminals and comvice one terminal of which is grounded, and prising means for applying a suitable elec- 1 means for applying a suitable electromotive tromotive force between two of said termi- 7 force between the respective ends of said nals an d for applying an electromotive loop and for applying an electromotive force of substantially equivalent mean eii'ecforce of substantially equivalent mean effectiveness alternately between such two and I tiveness alternately between said loop ends the third of said ter1i1inals,-in combination and the other terminal of said device. with a normally closed signal circuitloop 26. In a signal system ;current supply includingmanifesting me.ans, the respective mechanism having three terminals and comends of said loop connected to two of said prising means for applying a suitable electerminals, a common return conductor astromotive force between two of said termisociated with said loop, and a manifesting 2 nals and for applying an electromotive force device connected between said conductor and of substantially equivalent mean efi'ectivethe third of said terminals. a ness alternately between such two and the 31. In a signal,system;current supply third of said terminals, in combination mechanism having three terminals and comwith a normally closed signal circuit loop prising means 1' applying i Suitable B1 25 the respective ends of-which are connected tromotive force between two of said teri to two of said terminals, and a common reminals and for applying an electromotive turn conductor associated with said loop force of substantially equivalent mean efand connectedto the third of said te'rmi-' fectiveness alternately between such two nals. and the-third ofv said terminals,in com- 30 27.. In a signal system ;current supply bination with anormally closed signal cirmechanism having three terminals and com; cuit loop including manifesting means at prising means for applying a suitable electhe ends thereof, the respective ends of said tromotive'forcc between two of said termiloop connected to two of said terminals, rials and for applying an electromot ive force a common return conductor associated with 35 of substantially equivalent mean eifectivesaid loop, and a -manifesting device con- 1 .ness alternately between such two and the nected between said conductor and the third third of said terminals,in combination of said terminals. with a normally closed signal circuit loop 32. In a signal system ;.current supply the respective ends of which are connected .mechanism havingthree terminals and com- 40 to two of said terminals, a common return prising means for applying a suitable clecconductor associated with said loop, and a tromotive force between two of said termanifesting device connected betweemsaid minals and for applying an electromotive conductor and the third of said terminals. force of substantially equivalent mean 28. In a signal system ;-current supply effectiveness alternately between such two 45 mechanism having three terminals and comandathe third of said terminals,in comprising means for applying a suitable elecbination with a circuit having signal initromotive force between two of said termitiating'stations and manifesting means suitnals and for applying an electromotive ably connected thereto, the respective ends force of substantially equivalent mean eifecof said circuit connected to two of said ter- 60 tiveness alternately between such two and minals, and a common return conductor asthe third of said te1minals,-in.combinasociated with said circuit and connected tion with a normally closed signal circuit to thethirdof said terminals. loop serially including manifesting, means, 33. In a signal systcm; -current supply the respective ends of said loop connected to mechanism having-three terminals and com- 55 two of said terminals, and a common return prising means for applying a suitable elecconductor associated with said loop and conr tromotive force between two of said ter: nected to the third of said terminals. minals and for applying an electromotive 29. In a signal system ;current supply force of substantially equivalent mean efmechanism having three terminals and comfectiveness alternately between such two 00 prising means for applying a suitable elecand the third of said terminals,in comtromotive force between two of said termi bination with a circuit having signal ininals and for applying an electromotive force -tiating stations suitably connected thereto,

of substantially equivalent mean efiectivemanifesting devices through which the reness alternately between such two and the spective ends of said circuit are connectedthird of said terminals,in combination to two of said terminals, and a common return conduptor associated with said circuit and connected to the third of said terminals. s v M 34:. In a signal system ;current supply mechanism having three terminals and comprising means for applying a suitable electromotive force between two of said terminals and for applying an electromotive force of substantially equivalent mean effectiveness alternately between such two and the third of said terminals,in combination with a circuit having signal initiating stations and manifesting means suitably connected thereto, the respective ends of said circuit\ connected to two of said terminals, a common return conductor associated with said circuit, and a manifesting device connected between said conductor and the third of said terminals.

35. In a signal system;current supply mechanism having three terminals .and comprising means for applying a suitable electromotive force between two of said terminals and for applying an electromotive force of substantially equivalent mean "effectiveness alternately between such two and the third of said terminals,in combination with alcircuit having signal initiating stations suitably connected thereto, a common return conductor associated with said circuit, and manifesting devices two of which are connected between the respective ends of said circuit and two of said terminals and another of which is connected between the third of said terminals and said conductor.

36. In a signal system ;current supply mechanism having three terminals and comprising means for applying a suitable electromotive force between two of said terminals and for applying an electromotive force of substantially equivalent mean effectiveness alternately between such two and the third of said terminals,in co1nbination with a circuit having manifesting means and signal initiating statlons su1tably connected thereto, said stations each comprising means for formulating a code signal, the respective ends of said circuit connected to two of said terminals, and a commonreturn conductor associated with said circuit and connected to the third of said terminals. v

37. In a signal system;current supply mechanism having three terminals and comprising means for applying a suitable electromotive force between two of said terminals and for applying an electromotive force of substantially equivalent mean effectiveness alternately between such two andthe third of said terminals,in combination with a circuit having signal initiating stations suitably connected thereto and each comprising means for formulating a code signal, manifesting devices through '38. In a signal system ;'current supply merhanism having three terminals and comprising means for applying a suitable electromotive force between two of said terminals and for applying an electromotive force of substantially equivalent mean effectiveness alternately between such two and the'third of said terminals,in com bination with a circuit having manifesting meansand signal initiating stations suitably connected thereto, said stations each comprising means for formulating a: code signal, the respective ends of said'circuit connected to two'of said terminals, a common return conductor associated with said circuit, and a manifesting device connected between said conductor and the third of said terminals.

i 39. In a signal system;current supply mechanism having three terminals and com prising means for applying a suitable electromotive force between two of said terminals and for applying an electromotive force of substantially equivalent mean effective ness alternately between such two and the third ofsaid terminals, in combination with a circuit having signal initiating stations suitably connected thereto and each comprising means for, formulating acode signal, a common return conductor associated with said circuit, and manifesting devices two of the respective ends of said circuit and two of said terminals and another of which is connected between the third of said terminalsand said conductor.

40. In a signal system ;.'currentsupply mechanism having three terminals and comqirising means for applying a suitable electromotive force between two of said termi- 11:18 and for applying an electromotive force 0 ness alternately between such two and the which are connected between substantially equivalent mean efiective-' third of said terminals,-in combination I with a circuit connecting signal initiating stations and manifesting-means, said stations each comprising means for governing the effectiveness of a connection between said circuit and a common retprn conductor, therespective ends of said circuit connected to two of said terminals, and a common return conductor for said stations, said con- Y nals, and a common return conductor for said stations, said conductor connected to the third of said terminals.

, 42. In a signal system;current supply mechanism having three terminals and com- 16 prising means for applying a suitable eleci tromotive force between two of said terminals and for applying an electromotive force of substantially equivalent mean effectiveness alternately between such two 20 and the third of said terminals,in combination with a circuit having an associated common return conductor and connecting signal initiating stations and manifesting means, said stations each comprising means 26 for governing the effectiveness of a connection between said conductor and said circuit, the respective ends of said circuit connected to two of said terminals, and a manifesting device connected between said 30 conductor and the third of said terminals.

43. In a signal systems-current supply mechanism having. three terminals and comprising'means for applying a suitable electromotive force between two of said terminals and for applying an electromotive force of substantially equivalent mean effectiveness, alternately between such two and the third. of said termina1s,in combination with a circuit-having an associated common return conductor and connecting signal initiating stations, said stations each comprising means for governing the efl'ectiveness of a connection between-said conductor and said circuit, and manifesting devices two of which are connected between I the respective ends of said circuit and two of said terminals and another of which is connected betweenthe third of said termiinals and said conductor.

44. In a signal system current supply mechanism having three terminals and comprising means for applying a suitable electromotive force between two of said termi nals andfor applying an electromotive force .of substantially equivalent mean eifectiveness alternately between such-two and the third of said terminals,in combination with a circuit having an associated common return conductor and connecting signal initiaiting stations and manifestin means, said stations each comprising means or formulating a code signal and for governing the effectiveness of a connection between said conductor and said circuit,-the respective ends of said circuit connected'to two of said tromotive force between two of said terminals. and for applying an electromotive force of substantially equivalent mean eifectlveness alternately between such two and the third of said terminals,-in combination with a circuit connecting signal. initiating stations, said stations each comprising means for formulating a code signal and for governing the efiectiveness of a connection between said circuit and a common return conductor, manifesting devices through which the respective ends of said ClICHJlE are connectedto two of said terminals, and a common return conductor for said stations said conductor connected to the third oi said terminals. I

46. In a signal system ;current supply mechanism having three terminals and comprising means for applying a suitable, electromotive force between two of said terminals and for applying an electromotive force of substantially equivalent mean eiiectiveness alternately between such two and the third of saidterminals, in combination with a circuit having an associated common return conductor and connecting signal initiating stations and manifesting means, said stations each comprising means for formulating a code signal and for governing the effectiveness of a connection between said conductor and said circuit, the respective ends of said circuit connected to two of said terminals, and a manifesting device connected between said conductor and the third of said terminals.

47. In a signal system p-current supply mechanism having three terminals and com A prising means for applying a suitable electromotive 'force between two of said ter- 'minals and for applying an -electron1ot1ve force of substantially equivalent mean effectiveness alternately between such two and the third of said terminals,in combination with a circuithavin'g an associated common return conductor and connecting signal 1mtlatlng stations, said .statlons each comprising means for formulating a code signal and force of substantially equivalent mean effectiveness alternately between such two and the third ofsaid terminals',in combination with a normally closed signal circuit loop the respective ends of which are connected to the ungrounded terminals of said mechanism. n 7 X 49. In a signal sys-tem;-current supply mechanism having three terminals and com- 10,

prising means for applying a suitable electromotive force between two of said terminals and for applying an electromotive force of substantially equivalent mean efl'ee tiveness alternately between such two and the third of said terminals,in combina-' tion with a normally closedsignal circuit loop the respective ends of which are connected .to two of the terminals of said mechanism, and a manifestingdevice connected between the other of said terminals and the ground.

50. In a signal system ;current supply mechanism having three terminals and comprising means for applying a suitable electromotive force between two of said terminalsand for applying an electromotive force-of substantially equivalent mean effectiveness alternately between such two and l the third of said terminals,- i'n combination with a normally closed signal circuit loop,

- and manifesting devices two of which are terminal of said device.

connected between the respective ends of said loop and two of said terminals and another of which is connectedbetween the third of said terminals and the ground.

51. Ina signal system,'a normally closed signal circuit loop and a common return conductor asociated'therewith, in combination with apolyphase current supply source two of the phases of which are connected to the respective ends of said loop anda third phase of which is connectedto said conductor. j I

52. In a signal system,a normally closed signal circuit loop, a common return conductor associated therewith, and a manifesting deVice'toone terminal of which. said conductor is connected, 1n combination w th a polyphase current supply source two of the phases of which are connected .to the respective ends of said 100 and a third phase of which is connected to the other 53. In a signal system,a normally closed signal circuit loop serially including manifesting means, and a common return conductor associated with nation with a polyphase current supply source two of the phases of which are connected to the respective ends of said loop of whichis connected to and 'a third; phase said conductor.

54. Ina signal system,-a normally closed signal clrcuit loop including manifesting means at the ends thereof, and a common said loop, in combiare connected to the respective ends of said v loop and a third phase of which is con nected to said conductor. 55. In a signal system,-a normally closed signal circult loop including manifesting means, a common return conductor associated with said loop, and a manifesting de viceto one terminal of which said conductor isconnected, in combination with a polyphase current supply source two of the phases of which areconnected'to the respective ends of said loop and a third phase of which is connected of said device.

56. In a signal system,.-a normally closed signal circuit loop including manifesting means at the ends thereof, a common return conductor associated with said loop, anda -pha'se of which is connected to the other terminal of said device.

57; In a signai system,-a circuit having signal initiating stations and manifesting means suitably connected thereto, and a com mon return'conductor associated with said to the other terminal circuit, in combination with a polyphase current supply source two of the phases of which are connected to the respective ends of said circuit and a third phase of which is connected to. said conductor.

58. In a signal system,a circuit having manifesting devices connected at the ends thereof, signal initiating. stations'suitably connected to said circuit, and a common return conductor associated with said circuit, in, 'combination"with a polyphase current supply source two of the phases of which are connected tothe respective ends of said circuit and a thirdphase of which is connected to said conductor 59. In a signal-system,a circuit having slgnal lnltlitlflng stations and manifesting means suitably connected thereto, a com- 'mon return conductor associated with said circuit, and a manifesting devlce to one terminalof which said conductor is connected,

in combination with a polyphase current supply source two of thephases of which areconnected to the respective ends of said nected to the other terminal of said device.

60. In a signal system,a circuit having signal initiating stations suitably connected thereto, manifesting means connected at the circuit and a third phase of which'is con-,

ends of said circuit, a common return con- 1 ductor associated with said circuit, and a manifestmg device to one terminal of which said conductor 1s connected, in combination J ply source two of the-phases of which are connected to the respective ends of said, circuit and a third phase of which is connected to said conductor. a I

62. In a signal system, a circuit having manifesting devices included at the ends thereof, signal initiating stations suitably connected to said circuit and each comprising means for formulating a code-signal,

and a common return conductor associated with said circuit, in combination with a polyphase current supply source two of ,the phases of which are connected to the nesplective ends of said, circuit and a third p ase of which is connected to said conductor.

63. In a signal s'ystem,a circuit having manifesting means and signal initiating stations suitably connected thereto, said stations each comprising means for formulating a code signal. a common return conductor associated with said circuit, and a manitesting device to one terminal of which said conductor is connected, in combination with a polyphase current supply source two of the phases of which are connected to the respective ends of said circuit. and a third phase of which is connected to th other terminal of said-device. I

64. In a signal system -a circuit havin signal initiating stations suitably connected thereto and each comprising means for formulating a code signal, manifesting means included at the ends of said circuit, a com mon return conductor associated with said circuit, and a manifesting device to one terminal of which' said conductor is connected, in combination with a polyphase current Suppl; source of two of the phases of which are connected to the respective endsof said circuit and a third phase of which is connected to the other terminal of said device. i

65. In a signal system,a circuit having an associated common return conductor and connecting manifesting means and signal initiating stations, said stations each comprising means for governing the effectiveness of a connection between said conductor and said clrcult, 1n combinatlon with a poly phase current supply source two the phases of which are connected to the respective endsof said circuit and the third phase of which is connected to said conductor.

66. In a signal system,a circuit havin an associated common return conductor an including manifesting devices at the ends thereof, signal initiating stations suitably I I l connectedto said circuit and each compris ing means for governing the eifectiveness of a connection between said conductor and said circuit, in combination with a fpolyphase current supply source two 0 the phases of which are connected to the respective ends of said circuit and a third phase of which is connected to, said conductor.

67. In a signal system,a circuit having an associated common return conductor and connecting manifesting means and, signal initiating stations, said stations each comprising means for governing the effectiveness of a connection between said conductor and said circuit, and a manifesting device toone terminal of which said conductor is connected, in combination with a polyphase current supply source two of the phases of which are connected'to the respective ends of, said circuit and a third phase of which is connected to the other terminal of said device.

68. In a signal sys'tem,a circuit having an associated common return conductor and. including manifesting means at the ends thereof, signal initiating stations suitably connected to said circuit and each comprising means for governing the efi'ectiveness of a connection between. said conductor and said circuit, and a manifesting device to "one terminal of which said conductor is connected, in combination with a polyphase current supply source two of the phases of which. are connected to the respective ends of said circuit and a third phase of which is connected to the other terminal of said device.

r 69. In a signal system,a'circuit having 'an associated common return conductor and connecting manifesting means and signal initiating stations, said stations each ,comprisand for governing the effectiveness of aconnection between said conductor and said circuit, in combination with a polyphase current supply source two of the phases of which are connected to the respective ends of said circuit and a,thii'd phase of whichis connected to said conductor.

70. In a signal system,-a circuit having an associated common return conductor and including manifesting devices at the ends thereof, signal initiating stations suitably connected to said circuit and each comprising means for formulating a code si al and for governing the effectiveness 0 a connection between said conductor and said circuit in cbmb'mation with a polyphase current supply source two of the phases of which are connected to the respective ends of said circuit and a third phase of which is connected to said conductor.- 7

71. 'In a signal system,a,c1rcu1t having an associated common return conductor and connecting manifesting means and signal initiating stations, said stations each comprising means for formulating a code signal and for governing the effectiveness of a connection between said conductor and said vcircuit, and a manifesting device to one terminal of which said conductor is connected, in combination with a polyphase current supply source two of the phases of which are connected to the respective ends of said circuit and a third phase of which is connected'to the other terminal of said device.

72. In a signal system,a circuit having,

an associated common return conductor and.

' cuit, and a manifesting device to one termicuit and a third phase of which is connected nal of which said conductor is connected, in combination with a polyphase current supply source two of the phases of which are connected to the respective ends of said-cirto the other terminal of said device.

73. In a signal system,a normally closed signal circuit loop, in combination with a polyphase current supply source two of the phases of which are connected to therespective ends. of vsaid loop and a third phase of which is grounded.

74-. In a signal system,-a normally closed signal circuit loop and a manifesting device one terminal of which is grounded,

in combination with a polyphase current supply source two of the phases of which are connected to the respective ends of said loop and a third phase of which is connected to the other terminal of said device.

7 In a signal system,a normally closed signal circuit loop including manifesting means at the ends thereof, and a manifesting device one terminal of which is grounded, in combination with a polyphase current supply source two of the phases of which are connected to the res ective ends of said loop and a third phase 0 which is connected to the other terminalof said device.

76. In a signal system,a normally closed signal circuit loop, a common return conductor associated therewith, and means for applying a suitable electromotive force between the respective ends of said loop and for applying an electromotive force alternately between such loop ends and said conductor at such frequency as to be adapted to cause currentflow of suitable mean sig-.

naling eifectivenessbetween said conductor and either or both of said loop ends.

77. In a signal system,a normally closed signal circuitloop, a manifesting device, a common return conductor associated with said loop and connected to one terminal of said device, and means for applying a suitable electromotive force between the respective ends of said loop and for applying an electromotive force alternately between such loop ends and the other terminal of said device at such frequency as to be adapted to' cause currentflow of suitable mean signaling effectiveness between said device and either or both of said loop ends.

78. In a signal system,a normally closed signal circuit loopserially including manifesting means, a common return conductor associated with said loop,and means for applying a suitable electromotive force between the respective ends of said loop and for applying an electromotive force alternately between such loop ends and said conductor at such frequency as to be adapted to cause current flow ofsuitable mean signaling effectiveness between said conductor and either or both of said loop ends.

79. Ina signal system,a normally closed signal circuit loop including manifesting means at the ends thereof, a common re-.

turn conductor associated with said loop, and means for applying a suitable electromotive force between the respective ends of said loop and for applying an electromotive force alternately between such loop ends and said conductor at such frequency as to be adapted to cause current flow of suitable mean signaling effectiveness between said conductor and either orbothi of said loop ends.

80. In a signal system,a normally closed signal circuit loop including manifesting means, a common return conductor associated with said loop, a manifesting device to one terminal of which said conductor is connected, and means for applying a suitable electromotive force between the respective ends of said loop and for applying an electromotive force alternately between such loop ends and the other terminal of said device at such v frequency as to be adapted to cause current flow 'of suitable mean signaling effectiveness between said device and either or both of said loop ends.

81. In a signal system.-a normally closed signal circuit loop including manifesting means at the end thereof, a common return conductor associaed with said loop, a manifesting device to one terminal of which said conductor is connected, and means for applying a suitable electromotive force be tween the respective ends of said loop and forapplying an electromotive force alternately between such loop ends and the other terminal of said device at such frequency 

